Problem Statement

Given an array of positive integers height, where height[i] represents the height of the bar in the elevation map and each bar has width 1, return how much water it can trap after raining.

Examples

Example 1:

• Input: height = [4, 0, 3, 0, 2]

• Expected Output: 5
• Justification: The first and third bars form a container that traps 3 units of water. The third and fifth bars trap an additional 2 units. Therefore, the total trapped water is 5 units.

Example 2:

• Input: height = [1, 2, 1, 2, 1]